/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
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   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
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   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce::dsp
{

class FIRFilterTest final : public UnitTest
{
    template <typename Type>
    struct Helpers
    {
        static void fillRandom (Random& random, Type* buffer, size_t n)
        {
            for (size_t i = 0; i < n; ++i)
                buffer[i] = (2.0f * random.nextFloat()) - 1.0f;
        }

        static bool checkArrayIsSimilar (Type* a, Type* b, size_t n) noexcept
        {
            for (size_t i = 0; i < n; ++i)
                if (std::abs (a[i] - b[i]) > 1e-6f)
                    return false;

            return true;
        }
    };

   #if JUCE_USE_SIMD
    template <typename Type>
    struct Helpers<SIMDRegister<Type>>
    {
        static void fillRandom (Random& random, SIMDRegister<Type>* buffer, size_t n)
        {
            Helpers<Type>::fillRandom (random, reinterpret_cast<Type*> (buffer), n * SIMDRegister<Type>::size());
        }

        static bool checkArrayIsSimilar (SIMDRegister<Type>* a, SIMDRegister<Type>* b, size_t n) noexcept
        {
            return Helpers<Type>::checkArrayIsSimilar (reinterpret_cast<Type*> (a),
                                                       reinterpret_cast<Type*> (b),
                                                       n * SIMDRegister<Type>::size());
        }
    };
   #endif

    template <typename Type>
    static void fillRandom (Random& random, Type* buffer, size_t n) { Helpers<Type>::fillRandom (random, buffer, n); }

    template <typename Type>
    static bool checkArrayIsSimilar (Type* a, Type* b, size_t n) noexcept { return Helpers<Type>::checkArrayIsSimilar (a, b, n); }

    //==============================================================================
    // reference implementation of an FIR
    template <typename SampleType, typename NumericType>
    static void reference (const NumericType* firCoefficients, size_t numCoefficients,
                           const SampleType* input, SampleType* output, size_t n) noexcept
    {
        if (numCoefficients == 0)
        {
            zeromem (output, sizeof (SampleType) * n);
            return;
        }

        HeapBlock<SampleType> scratchBuffer (numCoefficients
                                            #if JUCE_USE_SIMD
                                             + (SIMDRegister<NumericType>::SIMDRegisterSize / sizeof (SampleType))
                                            #endif
                                             );
       #if JUCE_USE_SIMD
        SampleType* buffer = reinterpret_cast<SampleType*> (SIMDRegister<NumericType>::getNextSIMDAlignedPtr (reinterpret_cast<NumericType*> (scratchBuffer.getData())));
       #else
        SampleType* buffer = scratchBuffer.getData();
       #endif

        zeromem (buffer, sizeof (SampleType) * numCoefficients);

        for (size_t i = 0; i < n; ++i)
        {
            for (size_t j = (numCoefficients - 1); j >= 1; --j)
                buffer[j] = buffer[j-1];

            buffer[0] = input[i];

            SampleType sum (0);

            for (size_t j = 0; j < numCoefficients; ++j)
                sum += buffer[j] * firCoefficients[j];

            output[i] = sum;
        }
    }

    //==============================================================================
    struct LargeBlockTest
    {
        template <typename FloatType>
        static void run (FIR::Filter<FloatType>& filter, FloatType* src, FloatType* dst, size_t n)
        {
            AudioBlock<const FloatType> input (&src, 1, n);
            AudioBlock<FloatType> output (&dst, 1, n);
            ProcessContextNonReplacing<FloatType> context (input, output);

            filter.process (context);
        }
    };

    struct SampleBySampleTest
    {
        template <typename FloatType>
        static void run (FIR::Filter<FloatType>& filter, FloatType* src, FloatType* dst, size_t n)
        {
            for (size_t i = 0; i < n; ++i)
                dst[i] = filter.processSample (src[i]);
        }
    };

    struct SplitBlockTest
    {
        template <typename FloatType>
        static void run (FIR::Filter<FloatType>& filter, FloatType* input, FloatType* output, size_t n)
        {
            size_t len = 0;
            for (size_t i = 0; i < n; i += len)
            {
                len = jmin (n - i, n / 3);
                auto* src = input + i;
                auto* dst = output + i;

                AudioBlock<const FloatType> inBlock (&src, 1, len);
                AudioBlock<FloatType> outBlock (&dst, 1, len);
                ProcessContextNonReplacing<FloatType> context (inBlock, outBlock);

                filter.process (context);
            }
        }
    };

    //==============================================================================
    template <typename TheTest, typename SampleType, typename NumericType>
    void runTestForType()
    {
        Random random (8392829);

        for (auto size : {1, 2, 4, 8, 12, 13, 25})
        {
            constexpr size_t n = 813;

            HeapBlock<char> inputBuffer, outputBuffer, refBuffer;
            AudioBlock<SampleType> input (inputBuffer, 1, n), output (outputBuffer, 1, n), ref (refBuffer, 1, n);
            fillRandom (random, input.getChannelPointer (0), n);

            HeapBlock<char> firBlock;
            AudioBlock<NumericType> fir (firBlock, 1, static_cast<size_t> (size));
            fillRandom (random, fir.getChannelPointer (0), static_cast<size_t> (size));

            FIR::Filter<SampleType> filter (*new FIR::Coefficients<NumericType> (fir.getChannelPointer (0), static_cast<size_t> (size)));
            ProcessSpec spec {0.0, n, 1};
            filter.prepare (spec);

            reference<SampleType, NumericType> (fir.getChannelPointer (0), static_cast<size_t> (size),
                                                input.getChannelPointer (0), ref.getChannelPointer (0), n);

            TheTest::template run<SampleType> (filter, input.getChannelPointer (0), output.getChannelPointer (0), n);
            expect (checkArrayIsSimilar (output.getChannelPointer (0), ref.getChannelPointer (0), n));
        }
    }

    template <typename TheTest>
    void runTestForAllTypes (const char* unitTestName)
    {
        beginTest (unitTestName);

        runTestForType<TheTest, float, float>();
        runTestForType<TheTest, double, double>();
       #if JUCE_USE_SIMD
        runTestForType<TheTest, SIMDRegister<float>, float>();
        runTestForType<TheTest, SIMDRegister<double>, double>();
       #endif
    }


public:
    FIRFilterTest()
        : UnitTest ("FIR Filter", UnitTestCategories::dsp)
    {}

    void runTest() override
    {
        runTestForAllTypes<LargeBlockTest> ("Large Blocks");
        runTestForAllTypes<SampleBySampleTest> ("Sample by Sample");
        runTestForAllTypes<SplitBlockTest> ("Split Block");
    }
};

static FIRFilterTest firFilterUnitTest;

} // namespace juce::dsp
